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The Patriarchal Age

The time of the Biblical Patriarchs. Abraham, Isaac, and Jacob, is sometimes called the Patriarchal Age. If there is a kernel of truth to the Biblical stories, the Patriarchal Age probably goes back to the early third millennium. But the concept applies more broadly. A recent title says it: “A recent bottleneck of Y chromosome diversity coincides with a global change in culture.” This figure shows it.
The left panel shows effective population sizes based on Y chromosome DNA, transmitted down the male line. The right panel shows effective population sizes based mitochondrial DNA, transmitted down the female line. The dramatic dip on the left panel, where effective population sizes go way down in the last ten thousand years, means that there was a period, from the initial spread of major language families to near the dawn of history, where just a few men were leaving lots of descendants in the male line. This must reflect a time when polygyny – some men taking multiple wives, others not reproducing at all – was common. But this pattern probably reflects more than just polygyny. It probably also reflects a continuing advantage, carried over many generations, for some male lines of descent. In other words, back in the day, not just did Lord Y (or whoever) have many wives and many sons, but his sons, his sons’ sons. his son’s son’s sons, and so on, had many offspring. This probably implies some kind of long-term social memory, such that that the “Sons of Y” or the “House of Y” had a privileged position for many generations.

Australian Aborigines, subjects of our last two posts, often have high frequencies of polygyny, but mostly don’t keep track of genealogies over the long term. Men can tell you what kin terms they apply to other people, but they mostly don’t know their ancestry past a few generations. If I’m an Aborigine, it’s enough to know that my father called some other man “brother,” to know that that I call that man’s children my “siblings.” I don’t have to know the actual genealogy. But many Eurasian societies have been different. People can give you a line of begats stretching back many generations. For example, Kirghiz boys from a young age were expected to be able to tell you their “seven fathers”, i.e. their father, their father’s father, and so on, for seven generations. Having prominent ancestors inthe male line is a form of social capital. Even very large groups may claim descent from ancestors going way back. These stories – the tribes of Israel going back to the sons of Jacob, Greek patrilineages going back to the sons of Hellen (a guy, no relation to Helen of Troy), Indian Brahmins belonging to different ancestral gotras (patrilineal clans) going back to Vedic times – must have been heavily fictionalized. But maybe not completely.

Eurasian history is often told as the story the rise of states and empires. But it’s also the story of the rise of patrilineal descent groups (and the heavy policing of female sexuality to make sure of paternity in the male line). One thing we’ll see in posts to come is how the relationship between State and Clan played out differently in different civilizations.

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7 thoughts on “The Patriarchal Age”

Those two graphs terrify and fascinate me. They terrify me because of the suggestion of what, as a male, my life would probably have been like – a slave, or dead at 15. Maybe I’m overdramatizing? But they fascinate me in that they seem to offer an explanation of so much of male behavior, honor culture and so on.

By the way, do the Australian Aborigines show the same patterns in their mitochondrial DNA?

You’re over-dramatizing somewhat, because the spread of really successful patrilines presumably happened over many generations. Suppose in each generation the Sons of A have twice the reproductive success of other men – the bards sing of the undying fame of A, his descendants cash in on this reproductively, and the House of A is recognized as the legitimate ruling aristocracy. Then the A patriline will double its initial small representation in one generation, quadruple it in two generations, octuple it in three, and so on. In other words, moderate polygyny plus social memory allows much more dramatic skewing of Y-chromosome distributions than a situation where descendants of previously successful polygynists don’t have a special advantage.

An interesting observation about Australian Y-chromosome versus mitochondrial DNA is that mtDNA variation is more localized. It seems like Australian men were moving from place to place more than women, the opposite of the usual patrilocal pattern.

Well, I guess fears flourish best in a place where there is ignorance. I don’t really know much about how this mitochondrial DNA works.

However, one article I read about this claimed that at the trough, women were having 17x more reproductive success than males. My math says that at current rates of reproductive success (about 85% for women), that would imply that no more than 5% of all men successfully passed their genes on. But I guess that didn’t have to happen in a single generation.

Still, that seems like a really narrow filter, one that could easily produce a genetic, behavioral, or institutional change. But like I say, I don’t know much about how these things work.